1. Field of the Invention
This invention relates to a method of selecting a preceding vehicle, a preceding vehicle selecting apparatus, a recording medium for selecting a preceding vehicle.
2. Description of the Prior Art
A preceding vehicle selecting apparatus for emitting a transmission signal such as a light signal or a millimeter band radio wave signal over a predetermined angle range in front of a vehicle and detecting the reflection signal to recognize an obstacle around the vehicle, and selecting one from them as a preceding vehicle of the vehicle is known. Data regarding the preceding vehicle is used in an alarm apparatus for generating alarm regarding the preceding vehicle or an apparatus for controlling the vehicle velocity to maintain a predetermined distance from the preceding vehicle.
In this type of apparatuses, it is necessary to selecting the preceding vehicle traveling in front of a subject vehicle from the recognized objects. In selecting the preceding vehicle, it is general to use a steering angle sensor or a yaw rate sensor is used. For example, Japanese patent provisional publication No. 8-279099 discloses such a technique. In this technique, a parameter representing a probability of the preceding vehicle is used to prevent that the preceding vehicle is lost or an obstacle other than the preceding vehicle is erroneously recognized as the preceding vehicle. However, there is stile a possibility of erroneously recognizing a preceding vehicle if the subject vehicle is traveling on the straight line lane and the farther lane curves. In consideration of this problem, it is necessary to directly recognize the shape of the rode.
In this respect, there is a method of recognizing the road shape from delineators provided on the edges of the road as disclosed in Japanese Patent application provisional publication No. 5-288847. This technique is effective because of no cost up due to addition of no video sensor. However, if there is no delineator or the delineator cannot be detected due to dead angle by vehicles in front of the subject vehicle, there is the problem that the road shape cannot be detected.
Moreover, if remote delineators can be detected, the reliability of the preceding vehicle judgment is considered to be high. However, if only near delineators are detected or if other signboards other than the delineator are detected, there is the problem that the reliability of the preceding vehicle selection is low.
The aim of the present invention is to provide a superior method of selecting a preceding vehicle, a superior preceding vehicle selecting apparatus, and a superior recording medium for selecting a preceding vehicle.
Further, this invention aims to provide techniques of selecting of a proper preceding vehicle though the road shape cannot be recognized, as well as, to provide a higher accuracy preceding vehicle selection when the road shape can be recognized.
According to the present invention, a first aspect of the present invention provides a method of selecting one of recognized objects as a preceding vehicle of a subject vehicle, comprising the steps of: recognizing said objects in front of said subject vehicle; obtaining relative positions and relative velocities of said recognized objects; classifying said objects into stationary objects and moving objects on the basis of relative velocities of said objects to said subject vehicle; calculating a curvature of the lane on which said subject vehicle is traveling, on the basis of a turning condition and the velocity of said subject vehicle; calculating a probability that each of said moving objects travels on the same lane as said subject vehicle on the basis of said curvature and said relative position of each of said moving objects; recognizing a shape of the road, including the lane, in front of said subject vehicle, on the basis of distances to said stationary objects and angles of said stationary objects in the width direction of said subject vehicle and detecting a degree of recognizing said shape on the basis of said relative positions of said stationary objects and each of said moving objects; detecting a possibility that each of said moving objects exists on the same lane as said subject vehicle on the basis of the recognized shape of the road and said degree; calculating a compensation value for compensating said probability on the basis of the detected possibility; compensating said probability with said compensation value; and selecting one of said moving objects as the preceding vehicle on the basses of the compensated probability.
That is, the-same-lane probability that the object exists on the same lane on which said subject vehicle is traveling is calculated on the basis of the turning condition of said subject vehicle and the velocity of said subject vehicle and the relative position of the object. The calculated the-same-lane probability is compensated and then, the preceding vehicle is selected. The road shape in front of said subject vehicle is recognized on the basis of the distance from the object and the angle of the object in the width direction and a possibility that the object exits on the same lane as said subject vehicle is judged on the basis of the recognized road shape and the degree of recognition. The compensation value for compensating the-same-lane probability is calculated on the basis of the judging result. The-same-lane probability is compensated in accordance with the compensation value.
According to the present invention, a second aspect of the present invention provides a preceding vehicle selecting apparatus for a vehicle comprising: turning detection means for detecting a turning condition of said subject vehicle; curvature calculation means for calculating a curvature of the lane on which said subject vehicle is traveling, on the basis of the detected turning condition and a velocity of said vehicle; radar means for emitting a transmission signal within a predetermined angle range, in front of said vehicle, extending in a width direction of said vehicle and for detecting distances to objects reflecting said transmission signal and angles of said object in said width direction of on the basis of the reflected transmission signal; object recognizing means for obtaining relative positions and relative velocities of said objects to said vehicle on the basis of the distances and the angles in said width direction from said radar means and classifying said objects into stationary objects and moving objects on the basis of said relative velocities; the-same-lane probability calculation means for calculating a probability that each of said moving objects exists on the same lane as said subject vehicle, on the basis of the curvature from said curvature calculation means and the relative position of each of said moving objects from said object recognition means; road shape recognition means for extracting a part of said stationary objects which are effective for recognizing a shape of said road on the basis of said relative positions of said stationary objects, for recognizing said shape of said road in front of said subject vehicle on the basis of said relative positions of said extracted stationary objects, and for detecting a degree that said shape has been recognized in accordance with said relative positions of said stationary objects and each of said moving objects; the-same-lane judging means for judging the possibility that each of said moving objects exists on the same lane as said vehicle on the basis of said recognized road shape and said degree; compensation value calculation means for calculating a compensation value for compensating said probability of each of said moving objects on the basis of the judging result by said the-same-lane judging means; compensation means for compensating said probability from said the-same-lane probability calculation means with said compensation value for each of said moving objects; and preceding vehicle selection means for selecting the preceding vehicle of said vehicle from said moving objects on the basis of probabilities from said compensation means.
According to the present invention, a third aspect of the present invention provides a preceding vehicle selection apparatus based on the second aspect, wherein said the-same-lane judging means further judges whether said degree is such that said the-same-lane judging means will incorrectly judge the possibility in accordance with the recognized shape of said road, and when said the-same-lane judging means judges that said degree is such that the-same-lane judging means will incorrectly judge the possibility, said compensation value calculation means makes said compensation value zero.
According to the present invention, a fourth aspect of the present invention provides a preceding vehicle selection apparatus based on the second aspect, wherein said the-same-lane judging means further judges whether said degree is such that said shape of said road is recognized only at the range nearer than each of said moving objects, and when said the-same-lane judging means judges that said degree is such that said shape of said road is recognized only at the range nearer than each of said moving objects, said compensation value calculation means makes the absolute value of said compensation value for said one of said moving objects relatively small.
According to the present invention, a fifth aspect of the present invention provides a preceding vehicle selection apparatus based on the second aspect, wherein said the-same-lane judging means further judges whether said degree is such that said shape of said road is recognized only at the range nearer than each of said moving objects, and when said the-same-lane judging means judges that said degree is such that said shape of said road is recognized only at the range nearer than each of said moving objects, said compensation value calculation means makes the absolute value of said compensation value for said one of said moving objects relatively small in accordance with a relative distance of said recognized shape determined with relative positions of said part of said stationary objects.
According to the present invention, a sixth aspect of the present invention provides a preceding vehicle selection apparatus based on the second aspect, wherein said the-same-lane judging means further judges whether each of said moving object exists around one of edge of said road, and when said the-same-lane judging means judges that each of said moving object exists around one of edge of said road, said compensation value calculation means makes said compensation value relatively large in the negative direction.
According to the present invention, a seventh aspect of the present invention provides a preceding vehicle selection apparatus based on the second aspect, wherein said the-same-lane judging means judges the possibility that each of said moving objects exists on the same lane with reference to relations of said relative position of each of said moving objects and relative positions of said part of stationary objects.
According to the present invention, an eighth aspect of the present invention provides a preceding vehicle selection apparatus based on the second aspect, wherein said road shape reorganization means recognizes edges of said road, and said the-same-lane judging means judges the possibility that each of said moving objects exists on the same lane as said vehicle on the basis of each of said recognized edges and said degree, and judges a priority of said possibility on the basis of said degree every said recognized edge, and said compensation value calculation means calculates a compensation value for compensating said probability of each of said moving objects on the basis of the judging result of said the-same-lane judging means of which said priority judged for one of said recognized edges is higher than that for the other of said recognized edges.
According to the present invention, a ninth aspect of the present invention provides a preceding vehicle selection apparatus based on the eighth aspect, wherein said the-same-lane judging means further judges whether said degree is such that said shape of said road is recognized only at the range nearer than each of said moving objects, and when said the-same-lane judging means judges that said degree is such that said shape of said road is recognized only at the range nearer than each of said moving objects, said the-same-lane judging means judges said priority of said possibility to be relative low priority.
According to the present invention, a tenth aspect of the present invention provides a preceding vehicle selection apparatus based on the eighth aspect, wherein said the-same-lane judging means further judges whether each of said moving object exists around one of edge of said road, and when said the-same-lane judging means judges that each of said moving object exists around one of edges of said road, said the-same-lane judging means judges said priority to be relatively high.
According to the present invention, an eleventh aspect of the present invention provides a preceding vehicle selection apparatus based on the tenth aspect, wherein said the-same-lane judging means judges the priority that each of said moving objects exists on the same lane with reference to relations of said relative position of each of said moving objects and relative positions of said part of stationary objects.
According to the present invention, a twelfth aspect of the present invention provides a preceding vehicle selection apparatus based on the second aspect, wherein the-same-lane judging means detects a relative velocity vector of said part of stationary objects which are effective for recognizing a shape of said road, obtains a circle of which a tangent line vector corresponds to said relative velocity vector, and judges the possibility on the basis of said circle.
According to the present invention, a thirteenth aspect of the present invention provides a recoding medium readable by a computer for recording programs for a preceding vehicle selection apparatus for a vehicle comprising: turning detection means for detecting a turning condition of said subject vehicle; curvature calculation means for calculating a curvature of the lane on which said subject vehicle is traveling, on the basis of the detected turning condition and a velocity of said vehicle; radar means for emitting a transmission signal within a predetermined angle range, in front of said vehicle, extending in a width direction of said vehicle and detecting distances to objects reflecting said transmission signal and angles of said object in said width direction of on the basis of the reflected transmission signal; object recognizing means for obtaining relative positions and relative velocities of said objects to said vehicle on the basis of the distances and the angles in said width direction from said radar means and classifying said objects into stationary objects and moving objects on the basis of said relative velocities; the-same-lane probability calculation means for calculating a probability of existence of each of said moving objects on the same lane as said subject vehicle on the basis of the curvature from said curvature calculation means and the relative positions of each of said moving objects from said object recognition means; road shape recognition means for extracting a part of said stationary objects which are effective for recognizing a shape of said road on the basis of said relative positions of said stationary objects, recognizing a shape of said road on the basis of said relative positions of said extracted stationary objects, and detecting a degree that said shape has been recognized in accordance with said relative positions of said stationary objects and each of said moving objects; the-same-lane judging means for judging the possibility that each of said moving objects exists on the same lane as said vehicle on the basis of said recognized road shape and said degree; compensation value calculation means for calculating a compensation value for compensating said the-same-lane probability of each of said moving objects on the basis of the judging result by said the-same-lane judging means; compensation means for compensating said the-same-lane probability from said the-same-lane probability calculation means with said compensation value for each of said moving objects from said compensation value calculation means; and preceding vehicle selection means for selecting the preceding vehicle of said vehicle from said moving objects on the basis of the-same-lane probabilities from said compensation means.